72 Gooch and Heath — Iodometric Determination of Copper. 



without interfering appreciably with the estimation of 0*0010 

 grin, of copper and that the error introduced by the presence 

 of l cm3 , 2 cm3 and 3 em3 of sulphuric acid, hydrochloric acid and 

 nitric acid (free from nitrogen oxides) in 100 cra3 of solution is 

 scarcely appreciable. 



In Table Y are given the results of similar procedure applied 

 to larger amounts of copper. 



In the experiments of Series B and C the material for each 

 test was metallic copper standardized electrolytically. Portions 

 of this material were weighed and converted to the nitrate by 

 acting with nitric acid. The solution of the nitrate was evapo- 

 rated nearly to dryness and the residue dissolved and titrated 

 in the manner indicated. 



Table V. 



Effects of Acids upon the Determination of Larger Amounts 



of Copper. 



Copper 

 taken as 



Cu(N0 3 ) 2 



KI Volume 

 Approx- at begin- at end 

 Pres- imate ning of of titra 

 ent excess Acid titration tion 



- Copper 

 found 



Error 



/ grm. 



grm. 



grm. cm 3 . cm 3 . 

 A 

 "'inal volume between 110 c 



cm 3 . 



grm. 



grm. 





I 



m3 and 



120 cm3 . 









H 2 S0 4 cone. 









0-1200 



5-0 



4-5 2-5 100 



119 



0-1200 



±0-0000 



0-0900 



5-0 



4-5 3-0 100 



114 



0-0903 



+ 0-0003 



0-0900 



5-0 



4-5 3-5 100 

 HC1 cone. 



114 



0-0905 



+ 0-0005 



0-0900 



5-0 



4-5 2-0 100 



117 



0-0897 



— 0-0003 



0-1200 



5-0 



4-5 2-0 100 



119 



0-1195 



— 0-0005 



0-0900 



5-0 



4-5 3-0 100 



114 



0-0901 



+ 0-0001 



0-1200 



5-0 



4-5 3"0 100 



119 



0-1200 



±0-0000 



0-1200 



5-0 



4-5 3-5 100 



119 



0-1197 



— 0-0003 



0*0900 



5-0 



4-5 4-0 100 

 HNO3 cone. 



114 



0-0903 



+ 0-0003 



0-0900 



5-0 



4-5 1-0 100 



114 



0-0900 



±0-0000 



0-1050 



5-0 



4-5 1-5 100 



117 



0-1051 



+ 0-0001 



0-0900 



5-0 



4-5 2-5 100 



50 per cent 

 HC 2 H 3 2 



114 



0-0901 



+ 0-0001 



0-1200 



5-0 



4-5 3-0 100 



119 



0-1195 



— 0-0005 



0-0900 



5-0 



4-5 5-0 100 



114 



0-0898 



— 0-0002 



0-1050 



5-0 



4-5 10-0 100 



117 



0-1048 



— 0-0002 



